Burners and burner tube assemblies, including those used in gas grills, are well known. Most conventional gas grills include burner tube assemblies that provide a plurality of burner tubes, gas valves and a gas distribution manifold. Each burner tube has a length defined by an open end and a closed end and a plurality of outlet ports along the length of the burner tube between the open and closed ends. The open end of the burner tube typically includes an air shutter that is used to adjust the gas and combustion air mixture, as well as a venturi region to increase the velocity of the gas/air mixture in the tube. The open end of the burner tube is connected to the neck of a gas control valve, which is in fluid communication with a gas distribution manifold, which is in fluid communication with a gas source such as a tank.
For cost, manufacturing and other reasons, many conventional burner tubes are constructed from hollow welded circular tubing, often made from stainless steel. A venturi region is typically formed by pinching the tube near the open end of the burner tube. The venturi increases the velocity of the fuel/air mixture from the gas nozzle into the burner tube. An air shutter is also typically provided on the open end of the burner tube to adjust the fuel to air mixture.
Also for cost and other manufacturing reasons, the gas ports of typical burner tubes are punched into the tube from the outside of the tube to the inside, either on the top or sides of the tube. This results in burrs or other obstructions on the inside of the burner tube that can disrupt the flow of the fuel/air mixture and provide poor flame quality. Moreover, the flames produced by such burner tubes typically sit directly on the surface of the burner tube itself. This increases the temperature of the burner tube and can result in increased corrosion and clogging of the ports as well as a shorter life of the burner tube. In addition, many known burner tubes have a substantially uniform cross-section along their length that can result in uneven or inconsistent fuel pressure along the length of the tube. This can also negatively affect flame quality.
Thus, there is a need for improved burner tubes that provide improved flame characteristics and quality and which increase the life of the burner tube. There is also a need for burner tubes that enable smooth fuel/air flow throughout their length, as well as consistent pressure throughout the length of the burner tube. The present inventions solve the above described and other deficiencies and provide new features and advantages over known burner tubes.
There is also a need for improved venturis for use with burner tubes, either alone or in conjunction with the burner tubes of the present inventions. For example, it is possible, due to variation between gas train components, that turbulence can form at the upper portion of the burner tube adjacent to the gas outlet port. This can result in poor flame quality and/or the failure to ignite the gas/air mixture. Thus, there is a need for venturis that direct the turbulent gas/air mixture to the bottom of the burner tube and provide a smooth and consistent flow of the gas/air mixture along the top of the burner tube adjacent to the gas ports. This results in a more stable gas/air delivery system and better flame quality. The present inventions solve the deficiencies of know venturis and provide new features and advantages over known venturis, alone or in conjunction with the burner tubes of the present inventions.